Simin Dadparvar

Malignant astrocytomas treated with iodine-125 labeled monoclonal antibody 425 against epidermal growth factor receptor: A phase II trial☆

Twenty-five patients with primary presentation of malignant astrocytoma, astrocytoma with anaplastic foci, and glioblastoma multiforme were treated with surgical resection and definitive radiation therapy followed by intravenous or intra-arterial administration of Iodine-125 labeled monoclonal antibody-425, which binds specifically to human epidermal growth factor receptor. The patients presented with primary untreated disease, positive contrast enhanced computed tomography scans of the brain, and compatible clinical symptoms. In this Phase II clinical trial, the patients had surgical debulking or biopsy followed by definitively administered external beam radiation therapy and one or multiple doses (35 to 90 mCi per infusion) of radiolabeled antibody. The total cumulative doses ranged from 40 to 224 mCi. The administrations of the radiolabeled antibody were performed in most cases 4-6 weeks following completion of the primary surgery and radiation therapy. Ten patients had astrocytoma with anaplastic foci and 15 had glioblastoma multiforme. No significant life-threatening toxicities were observed during this trial. At 1 year 60% of the patients with astrocytoma with anaplastic foci or glioblastoma multiforme are alive. The median survival for both groups was 15.6 months.

Dual-time point FDG PET imaging in the evaluation of pulmonary nodules with minimally increased metabolic activity.

Purpose: FDG PET has high accuracy in the evaluation of lung nodules. A standardized uptake value (SUV) ≥2.5 is frequently used as a criterion for malignancy in this setting. However, some malignant nodules have only mild FDG activity with a SUV less than 2.5. Assessment of the etiology of lung nodules with only mild metabolic activity remains difficult. This study was undertaken to compare the accuracy of dual-time point and standard single-time FDG PET imaging in the evaluation of such lung nodules. Methods: Four hundred fifty-seven dual-time FDG PET scans for lung nodules were retrospectively analyzed. Among them, 46 met the selection criteria and were included for the final analysis. Five methods of interpreting FDG PET results were compared. These methods included visual analysis for both initial and delayed images; SUV analysis for both initial and delayed images in which a SUV of 2.5 is regarded as criteria for malignancy; and finally, the retention index analysis in which a 10% increase in SUV on the delayed images was regarded as an indication of malignancy. Results: The lowest accuracies came from the visual and single SUV analysis on the initial images. The visual and single SUV analyses on the delayed images produced increased accuracy. The highest accuracy (84.8%) was obtained when a retention index of more than 10% was used as criteria for malignancy. Conclusion: Dual-time FDG PET imaging has the potential for improving accuracy of a test in the evaluation of lung nodules with only borderline levels of increased metabolic activity.

Clinical utility of technetium-99m methoxisobutylisonitrile imaging in differentiated thyroid carcinoma : comparison with thallium-201 and iodine-131 Na scintigraphy, and serum thyroglobulin quantitation

Recently, technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) has been used to image thyroid carcinoma. A prospective study was performed to compare the efficacy of99mTc-MIBI to thallium-201 (201T1) scintigraphy in patients with differentiated thyroid carcinoma. The clinical utility of all radionuclide imaging modalities, i.e.,99mTc-MIBI,201Tl, and iodine-131 Na (131I-Na), as well as serum thyroglobulin estimation, was evaluated. Thirty-four post-thyroidectomy patients (age range: 26–76 years) underwent 45 studies. Histopathologies studied included fourteen papillary, eight papillaryfollicular, ten follicular, one Hürthle cell, and one medullary carcinoma of the thyroid. Following optimal stimulation of endogenous thyroid stimulating hormone (i.e, TSH >-50 mU/ml), the patients underwent201Tl and99mTc-MIBI scintigraphy. Concomitant131I-Na scintigraphy was performed and serum thyroglobulin levels were measured. Sixteen scan sets were performed prior to131I-Na ablation therapy. Twenty-nine scan sets were performed following131I-Na ablation therapy. The presence or absence of thyroid cancer was established by clinical, biochemical, radiologic, and/or biopsy findings. There was no significant difference in sensitivity and specificity of201Tl scintigraphy versus99mTc-MIBI scintigraphy in pre- and postablation studies.131I-Na scintigraphy with determination of thyroglobulin level was sufficient in preablation studies. Among postablation patients, the addition of99mTc-MIBI or201Tl offered a higher diagnostic yield. Between the201Tl and99mTc-MIBI studies, there was a concordance of 69% in preablation and 97% among postablation patients (P=0.027). It is concluded that99mTc-MIBI is a suitable alternative to201Tl scintigraphy in thyroid carcinoma, especially following thyroidectomy and131I-Na therapy.131I-Na scintigraphy with serum thyroglobulin is adequate in both pre- and postablation patients. Among the post-131I-Na ablation patients,99mTc-MIBI or201Tl is extremely valuable for tumor localization, especially when the131I-Na whole-body scan is negative. The combination of99mTc-MIBI or201Tl scintigraphy with131I-Na and serum thyroglobulin offers the highest diagnostic yield.

Paraneoplastic encephalitis associated with cystic teratoma is detected by fluorodeoxyglucose positron emission tomography with negative magnetic resonance image findings.

The role of fluorodeoxyglucose (FDG) positron emission tomography (PET) as a functional imaging technique used in the evaluation of a variety of malignancies has been well known. Paraneoplastic encephalitis is a rare central nervous complication, which has been reported in some tumors. Traditionally, magnetic resonance imaging of the brain is performed to aid in its diagnosis. The authors report a case of paraneoplastic encephalitis, associated with cystic teratoma, which had positive FDG-PET findings but appeared normal on magnetic resonance imaging.

FDG PET in detecting primary and recurrent malignant salivary gland tumors.

Purpose: The aim of this study was to assess the role of PET in the management of patients with primary malignant salivary gland (SG) tumor. Material and Methods: Sixty-one FDG PET studies in 48 patients (median age 58, range 28–89 years, 20 female, 28 male) who were diagnosed with malignant SG tumors were retrospectively analyzed. Thirteen were referred for initial diagnosis and staging while there was a suspicion of recurrence and/or metastatic disease in 48 patients during the follow-up period. Results: On PET examinations of 13 patients on initial presentation, 12 showed increased uptake in the primary lesion, while conventional methods (CT, MRI) were positive in 11 and were equivocal for 2 patients. Six patients with multiple nodal and 2 patients with distant metastases were detected by PET. Conventional methods demonstrated lymph node metastases in 5 of these patients. In the follow-up patient group, PET was inaccurate (false-negative or positive) in 4 (8%) patients with local recurrence, and in 4 (8%) with metastatic disease. However, 15 (31%) studies for recurrence and 7 (15%) for metastasis were false-negative with conventional radiologic methods. The sensitivity, specificity, and positive and negative predictive values for the detection of recurrent disease were 83%, 93%, 63%, and 98% for PET; 67%, 69%, 24%, and 94% for conventional methods, respectively. Overall sensitivity, specificity, positive and negative predictive values of PET for detecting metastatic disease were 93%, 96%, 82%, and 99%, while those of conventional methods were 80%, 95%, 75%, and 96%, respectively. Conclusion: These results demonstrate that FDG PET is not only superior to CT and/or MRI for staging at the initial presentation but also superior to conventional imaging methodologies for detecting local recurrence and regional lymph node and distant metastases in patients with malignant SG tumor.

Indium-111-labeled anti-EGFr-425 scintigraphy in the detection of malignant gliomas.

Background. The monoclonal antibody anti‐epidermal growth factor receptor (EGFr)antibody‐425, against the epidermal growth factor receptor, has the potential to bind specifically to gliomas and not normal brain tissue.1–3 A prospective study was conducted (1986–1988) to evaluate the use of Indium‐111 (111In)‐labeled anti‐EGFr‐425 in the localization of gliomas before radioimmunotherapy with Iodine‐125 (125I)‐labeled anti‐EGFr‐425.

Implications of lymphoscintigraphy in oncologic practice:Principles and differences vis-a-vis other imaging modalities

The prompt availability of interstitial lymphoscintigraphy and its utilization offer significant advantages over other techniques. Computed tomography represents a highly sensitive technique that suffers from lack of specificity in detecting small lesions. The expense and accessibility of machine time limit its usefulness as a routine survey procedure. Radiographic lymphangiography represents a tedious and difficult process necessitating identification of lymphatic channels for injection of the contrast material for visualization of the lymph nodes in the region being evaluated. With these demonstrated difficulties, the lymph node scanning technique has emerged as a simple, reliable, and reproducible technique for evaluation of multiple lymph node groups.

Follow-up FDG PET in the evaluation of unexplained focal activity in the abdomen.

Purpose: This study assessed the value of a follow-up FDG PET scan when the initial PET demonstrated unexplained findings of focal FDG uptake in the abdomen. Method: The records of 3634 patients with PET scans were retrospectively reviewed. Those patients who had follow-up PET scans after the initial PET scan showed unexplained FDG activity in the abdomen were further analyzed. The results from the second PET scan were compared with the follow-up data, which included the findings from other imaging modalities, clinical course, and biopsy or surgical pathology interpretations. Results: A total of 59 patients were included in the final analysis. The average time interval between the initial and the follow-up PET scans was 4.2 + 2.3 months. The follow-up PET provided a clear-cut diagnosis in 55 (93.2%) of these patients, whereas diagnoses in only 4 patients remained indeterminate. Follow-up PET scans were negative for abdominal malignancy in 38 patients. Thirty-five of these 38 patients with negative follow-up PET were proven to be without abdominal malignancy, with a negative predictive value of 92.1% (35 of 38). The follow-up PET was positive in 17 patients. Fifteen of these 17 patients with a positive follow-up PET scans were found to have malignancy in the abdomen with a positive predicative value of 88.2% (15 of 17). All 4 patients with indeterminate follow-up scans were proven not to have malignancy. Conclusion: Follow-up FDG PET scan provides an effective means for diagnosing unexplained findings in the abdomen that were previously detected on initial PET scan.

Unrecognized renal transplants as a potential source of false-positive interpretation of FDG PET.

Renal transplantation has become an effective therapy for patients with late-stage renal disease. Fluorodeoxyglucose (FDG) positron emission tomography (PET) is accepted as an important diagnostic technique in the evaluation of suspected or known malignancies or other disorders in the day-to-day practice of medicine. Because FDG is excreted from the kidneys into the urine, unrecognized renal transplants can appear as malignant lesions. Familiarity with the clinical history is a prerequisite in the correct interpretation of FDG PET images in this setting. In addition, FDG PET images should be correlated with anatomic images when such studies are available. When neither clinical history nor anatomic images are available, a combination of “abnormal” activity in the pelvis and absence of normal renal activity should raise suspicion of the existence of a renal transplant.

Triple-phase bone image abnormalities in Lyme arthritis.

Arthritis is a frequent manifestation of Lyme disease. Limited triple-phase Tc-99m MDP bone imaging of the wrists and hands with delayed whole-body images was performed in a patient with Lyme arthritis. This demonstrated abnormal joint uptake in the wrists and hands in all three phases, with increased activity seen in other affected joints on delayed whole-body images. These findings are nonspecific and have been previously described in a variety of rheumatologic conditions, but not in Lyme disease. Lyme disease should be considered in the differential diagnosis of articular and periarticular bone scan abnormalities.